If you are using a processor based system, you can simply use UART block and connect it to the processor bus. You can then write an embedded program to send the data out on the serial port.

However, if you are using simpler custom design you can build the UART by yourself which is basically a sort of shift register with precise clocking scheme.

You can read more at: http://www.fpga4fun.com/SerialInterface.html

In all cases, outside the FPGA, you will need a MAX232 chip for voltage level shifting and at the computer side you can use any terminal program to collect your data. Don't forget to set speed same as on the FPGA side.

Good luck with your project.

Ihab

 i'm using altera university program DE4 board.i can normally add a uart block but for the moment i need to khow how to connect it. in this case i need to use NIOS II to commande the uart block ?

if u have some documentation how to do it .

For the Altera University program, you can start by using the Hello World reference design, then you can use the following datasheet to help you adding the UART core and program it.

http://www-ug.eecg.toronto.edu/msl/nios_devices/datasheets/Altera%20RS-232.pdf

You can find step by step guide to build the NIOS system at:

https://www.altera.com/en_US/pdfs/literature/tt/tt_nios2_hardware_tutorial.pdf

Best regards